Data storage systems



y 7 J. R. MANHA'RDT Em. 3,512,974

DATA STORAGE SYSTEMS Filed Dec. 16, 1965 JEAN PAUL ARCHAMBAULT JOHN RICHARD MANHARDT INVENTORS W1 mm ATTORNEY United States Patent US. Cl. 96-48 12 Claims ABSTRACT OF THE DISCLOSURE An improved photographic developer system comprising a solution of metal ions which are at least as strong oxidizing agents as ionic copper, a reducing agent which can reduce these metal ions and a non-ionic sulphur containing surface active agent such as thioethers.

This invention relates to data storage systems. More precisely, the invention disclosed herein relates to data storage systems which include metal containing developer systems for retrieval of data stored in media of the systerns.

Physical developers comprise two essential ingredients: a photographic reducing agent and ions of metallic compounds which can be reduced as easily as copper. Such metal compounds include compounds of copper, mercury, silver, gold, platinum and the like. The photographic reducing agents normally present in physical developers include compounds which can reduce the aforesaid ions. Suitable reducing compounds include hydroquinone or derivatives thereof, oand p-aminophenol, p-methylaminophenol sulphate, p-hydroxyphenylglycine, oand pphenylenediamine, 1-phenyl-3-pyrazolidone and others which could be mentioned. Also, inorganic photographic reducing agents comprising ferrous, titanous and vanadous ions can be utilized. Oftentimes physical developers contain additional ingredients such as organic acids which can react with said metal compounds usually to form complex metal anions. Also, said developers oftentimes contain alkali metal sulfites which serve primarily to retard oxidation of the reducing agents.

It is well known in the art that physical developers are highly unstable primarily because of the inherent capability of the ingredients to spontaneously react with each other. This inherent instability is regarded as the prime factor which has prevented the extensive use of physical developers as conventional commercial photographic developers. For example, the instability of such developers generally manifests itself in the form of phenomena known to those in the art as sludging and mirroring which are merely different manners in which the precipitated reaction products of the developer ingredients are deposited from solution. At present, said sludging or mirroring occurs quite rapidly after the preparation of the developer. For example, sludging or mirroring Will generally be detected within a very short time after preparation, e.g. oftentimes within less than about five minutes. As sludging or mirroring becomes more pronounced, the quality of prints processed in the developer is adversely impaired. In any event, the appearance of either of the aforesaid phenomena generally indicates that the developer is exhausted or fast approaching exhaustion.

Many attempts have been made to solve the inherent instability of physical developers. For example, US. Pat. 3,157,502 to Jonker et a1. discloses improved physical developers. In accordance with the teachings of said patent, improved developer systems are obtained by the use therein of ionic surfactants. Also, said patent disice closes in detailed fashion, the ingredients of physical developers as well as many of the prior art solutions to the stability problem of such developers and said patent is incorporated herein by reference.

A principal object of the present invention is to provide an improved data storage system.

Another object of the present invention is to provide an improved data storage system which includes a developer system of improved stability.

Other objects and advantages of the present invention will in part appear hereinafter or will in part be apparent to those well skilled in the art.

We have discovered that the stability of physical developer systems can be improved in a surprisingly unexpected fashion by the use therein of a particular class of non-ionic surfactants. Broadly, the particular class of non-ionic surfactants which are useful in the practice of our invention are the non-ionic sulfur containing surface active agents known to the art generally as thioethers. Especially preferred non-ionic thioethers are the polyethylene glycol tertdodecyl thioethers. Others will be mentioned hereinafter.

Image or data storage media useful in the practice of our invention include those described in the aforesaid Jonker et a1. patent as well as media in which a photoconductor is a photosensitive component thereof. Said systems comprising photoconductors are described in more detail in commonly owned US. patent application Ser. No. 199,211, filed May 14, 196 2, by E. Berman et al. now abandoned. In accordance with the invention disclosed in the aforesaid application, media comprising radiation sensitive photoconductive materials such as zinc oxide, titanium dioxide, cadmium sulfide or indium oxide and the like are briefly exposed to a source of radiant energy. Such exposure establishes reversible image patterns in the media. The image patterns can be retrieved by contacting at least the exposed portion of the media with a chemical redox system capable of reacting on contact with the exposed portions to deposit thereon, species of the redox system which can be interpreted either directly or subsequently by visual readout.

The most preferred embodiment of our invention will be better understood by reference to FIG. 1 which illustrates in schematic fashion an arrangement of apparatus suitable for practicing our invention.

Referring now to FIG. 1, image patterns can be stored in image storage media of the present invention, 12, by exposure thereof to exposure means 14. Exposure means 14 includes source 16 of activating radiation, transparency 18, comprising an information image pattern desired to be stored and appropriate optical system 20, for focusing the image on medium 12. In general, image patterns can be stored in media ofthe present invention by exposure thereof to a source of radiation 16, having a wavelength such that the image storage media can absorb same. For example, the best results are realized by exposing media disclosed in the Berman et a1. application to light having a wavelength between about 0.2 micron to about 0.5 micron. However, since media suitable in the practice of the present invention can oftentimes include sensitizers such as dyes which can alter the spectral response thereof, other sources can be used. Accordingly, suitable light sources include mercury arc lamps, tungsten arc lamps, photoflash lamps and the like. The time of exposure will be determined primarily by such factors as the nature and strength of source 16 and the distance of the medium, 12, from the source, 16. Such factors are routine considerations normally encountered in conventional photographic processes. Thus, proper exposure time will be readily determined by one well skilled in the art. As an example, however, exposure times of considerably less 3 than 20 seconds, and more often than not less than about 5 seconds, are normally suitable.

After exposure, medium 12 is conveyed to tank 22. Tank 22 contains an aqueous or partially aqueous solution of a compound comprising silver, mercury, copper, gold or platinum, for example. Also, tank 22 comprises an organic reducing agent such as p-methylaminophenol sulfate or other suitable reducing agents such as those set forth in the aforesaid patent. The concentration of said reducing agent can vary over a wide range. For example, the .reducing agent can be present in amounts from 0.5 percent by weight of solution to 40 percent by weight. The application of the solution of tank 22 to medium 12 converts the image pattern stored therein to a visible form.

Oftentimes alkali metal sulfites--preferably sodium sulfite-can be included in the solution of tank 22. As mentioned, the sodium sulfite advantageously retards oxidation of the reducing agent. The preferred concentration of said sulfite is from about 0.5 percent by weight of solution to saturation concentrations or amounts somewhat higher.

In accordance with the practice of the present invention, the solution of tank 22 contains a non-ionic surfactant. Broadly, the non-ionic sufactants suitable in the practice of the present invention include those which are known to the art as thioethers and conform to the following generic formula:

where R is an alkyl radical with those having less than about 6 carbon atoms being preferred, or a polyhydric alcohol radical preferably having less than about 8 carbon atoms or polyoxyethylene glycol radical; S is sulfur and R is an alkyl radical preferably having less than about 14 carbon atoms. Accordingly, suitable representative non-ionic thioethers include butyl dodecyl thioether, ethyl octyl thioether, propyl heptyl thioether, methyl 3,4,5,6 tetrahydroxy hexyl thioether. Suitable concentrations of the non-ionic surfactant include those ranging from about 0.01 percent by weight of solution to about 3 percent by weight but amounts less than about 1.0 percent are most suitable. The solution of tank 22 can also contain an ionic surfactant if desired.

Broadly, the ionic surfactants suitable in the practice of our invention include those surfactants or dispersants which achieve dispersion by reason of the fact that they carry a charge which can be anionic or cationic in nature. The most preferred ionic surfactants are those which are cationic in nature. The following is a listing of some of the ionic surfactants suitable in the practice of the present invention:

Salts of primary alkylamines, the hydrophobic alkylaryl radical of which possesses at least 8 carbon atoms or mixtures of these compounds such as a primary dodecyl amine acetate;

Compounds, comprising a basic hydrophilic, nitrogen containing group which is bonded via an amide bond with the hydrophobic group;

Compounds, comprising a basic hydrophilic, nitrogen containing group which forms part of the morpholine ring system;

Compounds, comprising a basic hydrophilic, nitrogen containing group which forms part of a heterocyclic fivemembered ring;

Compounds comprising a basic hydrophilic, nitrogen containing group which forms part of a pyridine ring system;

Salts of primary alkylamines comprising a hydrophobic alkyl radical which possesses at least 8 carbon atoms, or mixtures of these compounds;

Compounds comprising a basic hydrophilic, nitrogen containing group which is bonded through an ether group with the hydrophobic group;

' .4 i Salts of sulphuric acid semi-esters of aliphatic alcohols;

and Alkylaryl sulphonates.

Suitable concentrations of the aforesaid surfactants range from 0.01 percent by weight of solution to about 3 percent by weight with amounts less than about 1 percent being preferred.

Medium 12 is generally permitted to remain in contact with the solution of tank 22 for'about 2 or 3 seconds but shorter or longer times can be suitably employed. After immersion in tank 22 additional processing steps can be applied to medium 12 such as washing, fixing and the like.

Details of manners of practicing our invention are set forth in the following examples. It is to be understood that the examples are illustrative in natureand in no way are they to be construed so as to limit our invention beyond those limitations expressly set forth in the present specification or claims which appear hereinafter.

EXAMPLE 1 Solutions of the formulations set forth in Table 1 were prepared.

TAB LE I 1 N ouio 260 is a polyethylene glycol tertdodceyl thioether.

In order to illustrate the relative stability of each of the above solutions, four milliliters of 0.2 N silver nitrate were added to each. After one hour, an exposed medium comprising titanium dioxide was first immersed in a 0.2 silver nitrate solution for about 2 seconds and then immersed in each of the above solutions for about 2 seconds. Sensitometric analysis of the images obtained in each media indicates that the effectiveness of solution B was about five times greater than that of solution A.

It is obvious from the above example that the nonionic surfactants of the present invention can effectively stabilize physical developers. Moreover, substantially the same results are obtained when the other thioethers heretofore mentioned are involved or metal compounds other than silver nitrate, such as compounds of gold, copper, mercury and the like, are involved or when other reducing agents heretoforementioned are included.

EXAMPLE 2 The following solutions were prepared:

Armour Armac 8D is an octylamine acetate; an ionic surfactant.

Aliquots of one milliliter of 0.2 N silver nitrate were added to each of the above solutions over a period of about 13 hours. After adding 20 milliliters of 'silver nitrate to each solution, substantial mirroring and sludging was apparent in solution F whereas solution E was substantially clear.

Many modifications of incidental'features offered in the above examples for the purposes of illustratingour invention may be introduced thereto withoutdeparting from the spirit and scope of our invention as defined in the appended claims.

Having described our invention as well as preferred embodiments thereof and manners of practicing same,

what we declare as new and desire to secure by US. Letters Patents is as follows:

1. An improved photographic developer composition which comprises a solution of ions of metallic compounds which can be reduced as easily as copper, a reducing agent which can reduce said ions; and a non-ionic surfactant conforming to the following generic formula:

where R is chosen from the group consisting of alkyl radicals, radicals of polyhydric alcohols and polyethylene glycol radicals; S is sulfur and R is an alkyl radical.

2. The composition of claim 1 wherein said non-ionic surfactant is a polyethylene glycol tertdodecyl thioether.

3. The composition of claim 1 wherein said ions of metallic compounds comprise silver ions.

4. The composition of claim 1 wherein said ions of metallic compounds comprise copper ions.

5. The composition of claim 1 wherein said ions of metallic compounds comprise at least one member of the group consisting of silver ions, copper ions, gold ions, platinum ions, and mercury ions.

6. The composition of claim 1 wherein said solution comprises silver nitrate.

7. The composition of claim 1 further including an ionic surfactnt.

8. The composition of claim 1 further including a primary dodecyl amine acetate.

9. In a photographic developer composition comprising ions of metallic compounds which can be reduced as easily as copper and a reducing agent for the ions of metallic compounds, the improvement comprising incorporating in the developer composition an non-ionic thioether containing surfactant.

10. A developer system as in claim 9 wherein the metal ions comprise a solution of at least one member of the group consisting of silver ions, copper ions, gold ions, platinum ions, and mercury ions; and wherein the concentration of non-ionic surfactants ranges from about 0.01 percent by weight to about 3 percent by weight of the solution of metal ions and reducing agent.

11. A developer system as in claim 1 wherein R is an alkyl radical having less than about 6 carbon atoms, or a polyhydric alcohol radical having less than about 8 carbon atoms, or a poyethylene glycol radical; S is sulfur and R is an alkyl radical having less than about 14 carbon atoms.

12. A developer system as in claim 1 wherein the nonionic surfactant is at least one member selected from group consisting of butyldodecyl thioether, ethyl octyl thioether, propyl heptyl thioether, and methyl 3,4,5,6 tetrahydroxy hexyl thioether.

References Cited UNITED STATES PATENTS 3,152,903 10/ 1964 Shepard et al. 96-64 3,252,798 5/ 1966 Jonker et al.

FOREIGN PATENTS 1,374,547 8/ 1964 France.

OTHER REFERENCES Technical Information on Dimethyl Sulfide, Crown Zellerbach Corp., Camas, Wash., 1961, p. 9.

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R. 

